Small, convenient to carry devices for nebulising perfume products and liquid cosmetics are already on the market.
In particular, they are nebulisation devices based on bottles whose compression generates and overpressure inside the bottle which causes the creation, through appropriate convergent channels, of a flow of air and a flow of liquid. Said currents are mixed just before the discharge orifice and the mechanical mixing of air and product in turbulent conditions generates the nebulisation. Such devices constitute a low cost alternative to mechanical nebulising micro-pumps.
From U.S. Pat. No. 4,186,882 granted on 5 Feb. 1980 a nebuliser for liquids is already known, which comprises a manually deformable container having a neck and an opening. The opening is provided with an elastic baffle provided holes, sustaining at its centre a nozzle for the distribution of liquid, connected to a suction tube. On the opening is also applied a covering element provided with a central discharge orifice. Between the covering element and the elastic baffle is created a mixing chamber in which are united the liquid coming from the interior of the container through the suction tube, and the air exiting due to the overpressure inside the container through the holes of the elastic diaphragm.
The adjustment of the flow rate and density of the jet is obtained by varying the distance between the covering element and the liquid distribution nozzle thanks to a screw-on coupling between the covering element and the neck of the bottle.
Lastly, on the covering element is applied a screw-on cap which closes the mixing chamber, preventing liquid from escaping outwards. Since the cap is removable, there are various easily intuited drawbacks linked to this fact.
German patent No. 10064630 discloses a nebuliser head provided with an integrated closing device which, rotating around the longitudinal axis, opens and closes the conduit for dispensing the product according to whether the passage holes are aligned or not. The conduit of the liquid flows into the air conduit, positioned transversely at the head of the former, in a rather distant point from the exit hole. This geometry has the advantage of exploiting also the Venturi effect to draw a suction on the liquid from the suction tube, but it requires a good air-liquid ratio and hence a sizeable quantity of air. The result is a questionable effectiveness in miniaturised systems.
U.S. Pat. No. 4,530,466 discloses a very simple nebuliser device, with a reduced number of components. The flow of air takes place through conduits obtained by means of grooves positioned on the periphery of the cylindrical seat of the suction tube. The conduits are obtained from the coupling of the suction tube with the nebuliser nozzle and each of them consists of a longitudinal segment—coaxial to the suction tube—and a radial terminal segment. The air is thus blown along said radial channels, orthogonally to the direction of the liquid, immediately behind the discharge hole. These channels do not have appropriate shape and dimensions to generate a vortex motion for the air, because they are obtained by coupling with the suction tube. For this reason, the dimensions of the channel are influenced by the correct fit of the suction tube and the cut of its end. This circumstance is particularly penalising when a similar air-liquid mixing system is to be adopted on miniaturised products. Moreover, there is a constraint on the direction of the spray, which must necessarily be along the axis of the bottle. While in some applications such a condition is in fact optimal (take the case of deodorants), in others an orthogonal spray to the axis of the bottle is preferred. This is especially true in those sectors (such as perfumes) where use of nebuliser micro-pumps that operate in this way is consolidated.